I. Field of the Invention
The present invention relates to telephone-style modular jacks and, more particularly, is directed towards a cap member utilized in combination with such modular jacks.
II. Description of Related Art
Telephone-style modular plugs and jacks are well known. They are widely used as general interconnect devices for a variety of types of electrical equipment. As utilized herein, the terms "modular jack" and "modular plug" connote the miniature, interchangeable, quick-connect-and-disconnect jacks and plugs developed by Western Electric Company and Bell Telephone Laboratories originally for use with telephone equipment. See, for example, U.S. Pat. Nos. 3,699,498; 3,850,497; and 3,860,316.
Several modular jacks have been proposed for directly coupling a modular plug to a printed circuit board. See, for example, U.S. Pat. Nos. 4,210,376; 4,457,570; 4,501,464; 4,577,921; and 4,717,217.
In prior U.S. Pat. No. 4,457,570, assigned to the same assignee as the present application, there is described an improved modular jack whose principal feature is the provision of conductors which enter the plug-receiving cavity of the jack from the rear of the jack, rather than from the front of the jack as with previous designs. This feature results in substantial economies as a result of the reduction in required conductor length, and the like.
An improved version of this modular jack is set forth in copending application Ser. No. 07/827,878, filed Jan. 30, 1992, assigned to the same assignee as the present application, which is specifically incorporated herein by reference. Modular jacks as set forth in the cited copending application are manufactured and sold by Virginia Plastics Company, Inc. of Roanoke, Va., licensee of the present assignee, as, for example, MODCOM-C.RTM. Part No. 020.000.229.
The latter modular jack provides many advantages over parts previously available. For one thing, contact failure due to overstress is greatly reduced. The signal transfer surface area between the male and female conductors is optimized. Uniform contact resistance is obtained independently of the depth of insertion of the plug into the jack, and the likelihood of vibration-triggered open circuits is reduced. Finally, assembly and manufacturing are greatly simplified over prior designs. These improvements resulted from modifications to the housing and contact structure that are set forth in full in the referenced copending application, and which will be explained briefly hereinafter.
Despite the great improvement manifested by the MODCOM-C.RTM. connectors over the prior art, a few areas remain for further improvement. For example, while the configuration of the housing and conductors greatly minimizes overstressed contacts under normal use, the contacts can nevertheless be overstressed in situations where, for example, someone inserts an improper size of modular plug into the modular jack. Most frequently, the outer contacts of the jack are the ones which are caused to over extend upwardly into an overstressed condition.
Although overstressing the conductors is in and of itself not desirable, since thereafter the conductors may not operate with optimum contact pressure, there is another danger associated with overstressing these contacts. Namely, if stretched too far upwardly out of the housing, the contacts can touch the exposed surface of an adjacent panel or circuit board and produce an undesirable inadvertent electrical or ground connection.
Another situation which can occur in high voltage conditions is arcing across the jack cap and contacts. This is believed to result in part from an air gap that is created adjacent the contacts. It is also possible in such a situation for the jack cap to lift off the housing. It would be highly desirable if some means could be provided for minimizing high voltage arcing, and for keeping the jack cap in place on the housing.
It is towards overcoming the additional deficiencies noted above that the present invention is advanced.